Conventional plasticizer compositions that include (DOTP) also include an influential amount of impurities or byproducts that restrict or preclude certain applications of the conventional plasticizer composition.
Conventional plasticizer compositions are prepared by conventional methods. Typically during the conventional methods, DOTP is prepared by reacting 2-ethylhexanol and terephthalic acid in the presence of a catalyst. Certain reaction conditions used in the conventional methods have a tendency to decompose the 2-ethylhexanol and/or the titanium catalyst to form a variety of decomposition products. These decomposition products subsequently react with terephthalic acid to produce the impurities. Typically, the impurities include a di-ester according to Formula I:
where R1 is a straight-chain or branched alkyl group having from 1 to 13 carbon atoms, and R1 is different than 2-ethylhexane
One of the most prevalent and influential impurities is methyl(2-ethylhexyl) terephthalate (MOTP). Conventional plasticizer compositions include the di-ester according to Formula I in an amount greater than 0.1 parts by weight based on 100 parts by weight of the conventional plasticizer composition. Typically, the conventional plasticizer composition includes the di-ester according to Formula I in an amount greater than 1, 1.5, or 2, parts by weight based on 100 parts by weight of the conventional plasticizer composition.
In addition to the di-ester according to Formula I, conventional plasticizers typically also include other impurities formed from the reaction product of (1) terephthalic acid and (2) decomposition products of 2-ethylhexanol and/or decomposition products of the titanium catalyst.
These impurities are chemically similar to DOTP and, as such, cannot be removed through conventional separation techniques (e.g. washing, filtering, distilling, etc.). As such, these impurities, especially MOTP, result in increased volatility and fogging of the conventional plasticizer composition and articles, films, or compositions containing the conventional plasticizer composition. As such, the presence of the impurities contained within the conventional plasticizer composition restrict or preclude the use of the conventional plasticizer composition in a variety of articles, films, and various other compositions. Accordingly, there remains an opportunity to develop an improved plasticizer composition.